WordPress at a glance
filter is not described

attachment_icon filter-hook . WP 1.0

Usage

add_filter( 'attachment_icon', 'filter_function_name_6652', 10, 2 );
function filter_function_name_6652( $icon, $ID ){
	// filter...

	return $icon;
}
$icon
-
$ID
-

Where the hook is called

get_attachment_icon()
attachment_icon
wp-includes/deprecated.php 1953
return apply_filters( 'attachment_icon', $icon, $post->ID );

Where the hook is used (in WP core)

Does not used.